Seismic Behavior of K-Braced Framing Systems

Three 10-story three-bay structures having K-braced framing systems are designed for seismic loads according to building code requirements. Members are proportioned by standard allowable stress procedures. The frames are subjected to strong ground motion and the inelastic response of the three systems is evaluated and compared. Results show that increased ductility requirements occur in regions adjacent to discontinuities in lateral stiffness. The addition of an outrigger truss at the top of the frame tends to force more of the inelastic deformation into the girders and bracing rather than the columns. The fully braced systems are very effective in controlling lateral displacement.